init_connect can be used to disable foreign key checks.
mysql> SET GLOBAL init_connect='SET foreign_key_checks = 0';

As well something similar for the GLOBAL options my.cnf file.
init_connect='SET foreign_key_checks = 0';

The super user will bypass the init-connect directives. So the user without the super privilege can take benefit of this setting.

Here is the list error codes mysql will return when it fails to connect to the mysql instance.

101 error: Can not connect to MySQL server (101)
102 error: '(proxy) all backends are down'
103 error: 'Access denied for user 'user'@'10.10.10.10' (using password: NO)'
104 error: 'Access denied for user 'user'@'10.10.10.10' (using password: YES)'
105 error: 'Host '10.10.10.10' is not allowed to connect to this MySQL server'
111 error: 'Lost connection to MySQL server at 'reading initial communication packet', system error: 111'
113 error: 'Lost connection to MySQL server at 'reading initial communication packet', system error: 113'
114 error: Unknown MySQL server host (3)

If you are getting too many emails from nagios service, you can create a filter in gmail.
From: nagios@company.com
to: shantanu.oa+nagios@gmail.com
Doesn't have : (db1 OR db2 OR localhost)

Do this: Skip Inbox, Apply label "company/nagios", Never send it to Spam

Download and Install redis from http://www.redis.io/download or use the following commands on the target server.

$ wget http://redis.googlecode.com/files/redis-2.2.8.tar.gz
$ tar xzf redis-2.2.8.tar.gz
$ cd redis-2.2.8
$ make

Start the redis server. To start the redis server please use the following command
$src/redis-server

configure the redis server ip in the Java properties file (cache.server) and ip (cache.port). The default port is 6379.

Important things to remember about Linux date:

* /etc/sysconfig/clock sets whether the hardware clock is stored as UTC or local time.
* Symlink /etc/localtime to /usr/share/zoneinfo/... to set your timezone.
* Run ``date MMDDhhmm'' to set the current system date/time.
* Type ``/sbin/hwclock --systohc [--utc]'' to set the hardware clock.

The default 8pt Tahoma font looks very small in Skype. It can be changed to 11pt Times New Roman. Tools - Option - IM & SMS - IM appearance - Change font

// copy the file to RAM - 30 times faster
cp -af /root/100mb.bin /dev/shm/

// increase it to 4GB
mount -o remount,size=4G /dev/shm

// new memory device
mkdir -p /var/www/www.mysite.com/ramdrive
mount -t tmpfs -o size=500M,mode=0744 tmpfs /var/www/www.mysite.com/ramdrive

// add it to /etc/fstab to make it permanent:
tmpfs /var/www/www.mysite.com/ramdrive tmpfs size=500M,mode=0777 0 0

660 mysql data dir
700 home directory
777 world writeable files
chmod +x asper.sh OR (chmod 754 asper.sh)

Default value of kernel net.ipv4.tcp_max_syn_backlog is 2048, increase it to 8192. Default value of net.core.somaxconn kernel setting is 128 and can be increased to 1000
MySQL parameter back_log which has default value of just 50. You may want to set it to 1000 or even higher.

If innodb_fast_shutdown is set to 0, the log files are purged when mysqld shuts down - larger files mean a longer shutdown time. The default for innodb_fast_shutdown is 1, which
means that the log files are not purged before a shutdown. A value is 2 simulates a crash, and at the next startup InnoDB will do a crash recovery.
This can be useful when testing to see approximately how long InnoDB takes to recover from a crash, to determine if the size of your log files is too large.